Conventionally, laser equipment capable of obtaining a laser beam with a narrow radiation angle in a plurality of bands has been demanded. For example, in Non-Patent Document 1, by using a PCSEL (Photonic Crystal Surface Emitting Laser), a narrow radiation beam with a beam spread angle of 1° or less can be provided by a simple configuration. Patent Document 1 discloses a semiconductor wavelength-variable laser light source that uses a diffraction grating as an external resonator. Patent Document 2 discloses a structure that varies the wavelength by adjusting the temperatures of a plurality of semiconductor DFB laser elements.
In recent years, in photonic crystal laser elements, particularly in PCSELs, higher output with narrow radiation and high beam quality has been realized. Unlike conventional semiconductor laser light sources, a PCSEL outputs a circular and narrow radiation beam, and has the advantage that a subsequent optical system can be significantly simplified, and wavelength conversion without a collimating lens that was conventionally impossible has also been demonstrated. The high beam quality of the PCSEL enables micro-condensing up to a diffraction limit, so that high energy density can be realized. Based on these superior features, various applications to microfabrication, high-resolution sensing, and lens-free structures, etc., have been expected.